This invention relates generally to separation of particles from mixtures and, more specifically, to flow cytometers for analyzing and sorting biological particles.
Flow cytometry is a valuable method for the analysis and isolation of biological particles such as cells and constituent molecules. As such it has a wide range of diagnostic and therapeutic applications. The method utilizes a fluid stream to linearly segregate particles such that they can pass, single file, through a detection apparatus. Individual cells can be distinguished according to their location in the fluid stream and the presence of detectable markers. Thus, a flow cytometer can be used to produce a diagnostic profile of a population of biological particles. For example, flow cytometry has been used to measure the decline or maintenance of immune cells during the course of treatment for HIV infection and to determine the presence or absence of tumor cells for prognosis and diagnosis of cancer patients.
Isolation of biological particles has been achieved by adding a sorting or collection capability to flow cytometers. Particles in a segregated stream, detected as having one or more desired characteristics, are individually isolated from the sample stream by mechanical or electrical removal. This method of flow sorting has been used to separate sperm bearing X and Y chromosomes for animal breeding, to sort chromosomes for genetic analysis, to isolate cells bearing specific antigens and to identify new organisms from complex biological populations.
Biological particles isolated by flow sorting can be used for a variety of diagnostic or therapeutic applications. However, impurities that co-fractionate with a biological particle of interest in a flow sorting method can produce false results in a diagnostic assay or can have adverse consequences in a therapeutic procedure. Thus, flow sorting methods often require decontamination procedures to remove unwanted residual materials between sample applications. One method of decontaminating a flow system is to flush or purge the devices that come into contact with sample. Such methods can be time consuming and costly and are often incomplete.
Currently, flow cytometers are bulky instruments that occupy large amounts of valuable laboratory and clinic space. Reduction in flow cytometer size has previously come at the expense of functionality or performance. One approach that has been used to minimize the space required for flow cytometry has been to design the instruments to replace multiple components with alternative components that are interchangeable. For example, multilaser flow cytometers have been made more compact by replacing multiple lasers and their optical paths with a single optical path through which different lasers can be separately directed. In this format a single laser is used while alternative lasers can be omitted or stored at a separate location. A disadvantage of this approach is that interchanging components can be time consuming, thereby reducing the throughput of the instrument or precluding the full range of analyses available for a single sample.
Thus, there exists a need for a flow cytometer that can be efficiently decontaminated. A need also exists for a flow cytometer having a variety of functions available in a compact format. The present invention satisfies these needs and provides related advantages as well.